Sparta and Athens had very different governments. Sparta was a militaristic state. This means that all decisions made by the government revolved around the wants and needs of the military. This resulted in Sparta developing one of the strongest armies in the world during this era.
Athens on the other hand had a form of democracy. A democracy is when individual citizens have a say in what laws are made and what representatives there are in the government. This gave the average Athenian much more political power in comparison to Sparta.
The United States involvement in the recent events in Rwanda can best be described as intervention. Involvement at all rules out isolation and diplomacy exists as synonymous to international affairs. The actions wouldn't be imperialistic because the US isn't trying to take control of Rwandan affairs thus it must be intervention - a direct involvement in an effort to allow the nation to conduct its own affairs.
